The present invention relates to a method for enhancing the electrical properties of compound semiconductor materials. More particularly, the invention relates to a method for enhancing electron mobility in N type III-V semiconductor materials.
Binary, ternary, and quaternary compound semiconductor materials are frequently used in electronic devices which are to be operated at high frequencies. For example, binary III-V compounds such as GaAs, InP, and InAs are commonly used in the fabrication of microwave FETs and devices for gigabit-rate logic applications. Compound semiconductor materials are used because they intrinsically provide greater electron mobility than silicon or germanium materials.
In the fabrication of a compound semiconductor device one typically starts with a semi-insulating substrate and then provides an active layer on a surface of the substrate. Conventional techniques for forming the active layer include epitaxial growth and ion implantation. For example, to create an N type active layer, electron donor impurities are introduced during either the epitaxial growth or the ion implantation. In a III-V material such as GaAs, N type dopants include sulfur and silicon, and an active layer can be formed as described in ION IMPLANTATION OF SULFUR AND SILICON IN GaAs, S. G. Liu et al., RCA Review, Vol. 41, 1980, pp. 227-262.
In the present invention a method for enhancing the electron mobility of N type GaAs is disclosed. However, it should be recognized that although the invention is described in terms of experimentation with GaAs, it is expected that other III-V materials, as well as ternary and quaternary materials, will behave in a similar manner.